﻿namespace org.apache.lucene.analysis.fi
{

	/*
	 * Licensed to the Apache Software Foundation (ASF) under one or more
	 * contributor license agreements.  See the NOTICE file distributed with
	 * this work for additional information regarding copyright ownership.
	 * The ASF licenses this file to You under the Apache License, Version 2.0
	 * (the "License"); you may not use this file except in compliance with
	 * the License.  You may obtain a copy of the License at
	 *
	 *     http://www.apache.org/licenses/LICENSE-2.0
	 *
	 * Unless required by applicable law or agreed to in writing, software
	 * distributed under the License is distributed on an "AS IS" BASIS,
	 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
	 * See the License for the specific language governing permissions and
	 * limitations under the License.
	 */

	/* 
	 * This algorithm is updated based on code located at:
	 * http://members.unine.ch/jacques.savoy/clef/
	 * 
	 * Full copyright for that code follows:
	 */

	/*
	 * Copyright (c) 2005, Jacques Savoy
	 * All rights reserved.
	 *
	 * Redistribution and use in source and binary forms, with or without 
	 * modification, are permitted provided that the following conditions are met:
	 *
	 * Redistributions of source code must retain the above copyright notice, this 
	 * list of conditions and the following disclaimer. Redistributions in binary 
	 * form must reproduce the above copyright notice, this list of conditions and
	 * the following disclaimer in the documentation and/or other materials 
	 * provided with the distribution. Neither the name of the author nor the names 
	 * of its contributors may be used to endorse or promote products derived from 
	 * this software without specific prior written permission.
	 * 
	 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" 
	 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 
	 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 
	 * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE 
	 * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR 
	 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF 
	 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS 
	 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN 
	 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) 
	 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
	 * POSSIBILITY OF SUCH DAMAGE.
	 */

	using org.apache.lucene.analysis.util;
//JAVA TO C# CONVERTER TODO TASK: This Java 'import static' statement cannot be converted to C#:
//	import static org.apache.lucene.analysis.util.StemmerUtil.*;

	/// <summary>
	/// Light Stemmer for Finnish.
	/// <para>
	/// This stemmer implements the algorithm described in:
	/// <i>Report on CLEF-2003 Monolingual Tracks</i>
	/// Jacques Savoy
	/// </para>
	/// </summary>
	public class FinnishLightStemmer
	{

	  public virtual int stem(char[] s, int len)
	  {
		if (len < 4)
		{
		  return len;
		}

		for (int i = 0; i < len; i++)
		{
		  switch (s[i])
		  {
			case 'ä':
			case 'å':
				s[i] = 'a';
				break;
			case 'ö':
				s[i] = 'o';
				break;
		  }
		}

		len = step1(s, len);
		len = step2(s, len);
		len = step3(s, len);
		len = norm1(s, len);
		len = norm2(s, len);
		return len;
	  }

	  private int step1(char[] s, int len)
	  {
		if (len > 8)
		{
		  if (StemmerUtil.EndsWith(s, len, "kin"))
		  {
			return step1(s, len - 3);
		  }
		  if (StemmerUtil.EndsWith(s, len, "ko"))
		  {
			return step1(s, len - 2);
		  }
		}

		if (len > 11)
		{
		  if (StemmerUtil.EndsWith(s, len, "dellinen"))
		  {
			return len - 8;
		  }
		  if (StemmerUtil.EndsWith(s, len, "dellisuus"))
		  {
			return len - 9;
		  }
		}
		return len;
	  }

	  private int step2(char[] s, int len)
	  {
		if (len > 5)
		{
		  if (StemmerUtil.EndsWith(s, len, "lla") || StemmerUtil.EndsWith(s, len, "tse") || StemmerUtil.EndsWith(s, len, "sti"))
		  {
			return len - 3;
		  }

		  if (StemmerUtil.EndsWith(s, len, "ni"))
		  {
			return len - 2;
		  }

		  if (StemmerUtil.EndsWith(s, len, "aa"))
		  {
			return len - 1; // aa -> a
		  }
		}

		return len;
	  }

	  private int step3(char[] s, int len)
	  {
		if (len > 8)
		{
		  if (StemmerUtil.EndsWith(s, len, "nnen"))
		  {
			s[len - 4] = 's';
			return len - 3;
		  }

		  if (StemmerUtil.EndsWith(s, len, "ntena"))
		  {
			s[len - 5] = 's';
			return len - 4;
		  }

		  if (StemmerUtil.EndsWith(s, len, "tten"))
		  {
			return len - 4;
		  }

		  if (StemmerUtil.EndsWith(s, len, "eiden"))
		  {
			return len - 5;
		  }
		}

		if (len > 6)
		{
		  if (StemmerUtil.EndsWith(s, len, "neen") || StemmerUtil.EndsWith(s, len, "niin") || StemmerUtil.EndsWith(s, len, "seen") || StemmerUtil.EndsWith(s, len, "teen") || StemmerUtil.EndsWith(s, len, "inen"))
		  {
			  return len - 4;
		  }

		  if (s[len - 3] == 'h' && isVowel(s[len - 2]) && s[len - 1] == 'n')
		  {
			return len - 3;
		  }

		  if (StemmerUtil.EndsWith(s, len, "den"))
		  {
			s[len - 3] = 's';
			return len - 2;
		  }

		  if (StemmerUtil.EndsWith(s, len, "ksen"))
		  {
			s[len - 4] = 's';
			return len - 3;
		  }

		  if (StemmerUtil.EndsWith(s, len, "ssa") || StemmerUtil.EndsWith(s, len, "sta") || StemmerUtil.EndsWith(s, len, "lla") || StemmerUtil.EndsWith(s, len, "lta") || StemmerUtil.EndsWith(s, len, "tta") || StemmerUtil.EndsWith(s, len, "ksi") || StemmerUtil.EndsWith(s, len, "lle"))
		  {
			return len - 3;
		  }
		}

		if (len > 5)
		{
		  if (StemmerUtil.EndsWith(s, len, "na") || StemmerUtil.EndsWith(s, len, "ne"))
		  {
			return len - 2;
		  }

		  if (StemmerUtil.EndsWith(s, len, "nei"))
		  {
			return len - 3;
		  }
		}

		if (len > 4)
		{
		  if (StemmerUtil.EndsWith(s, len, "ja") || StemmerUtil.EndsWith(s, len, "ta"))
		  {
			return len - 2;
		  }

		  if (s[len - 1] == 'a')
		  {
			return len - 1;
		  }

		  if (s[len - 1] == 'n' && isVowel(s[len - 2]))
		  {
			return len - 2;
		  }

		  if (s[len - 1] == 'n')
		  {
			return len - 1;
		  }
		}

		return len;
	  }

	  private int norm1(char[] s, int len)
	  {
		if (len > 5 && StemmerUtil.EndsWith(s, len, "hde"))
		{
			s[len - 3] = 'k';
			s[len - 2] = 's';
			s[len - 1] = 'i';
		}

		if (len > 4)
		{
		  if (StemmerUtil.EndsWith(s, len, "ei") || StemmerUtil.EndsWith(s, len, "at"))
		  {
			return len - 2;
		  }
		}

		if (len > 3)
		{
		  switch (s[len - 1])
		  {
			case 't':
			case 's':
			case 'j':
			case 'e':
			case 'a':
			case 'i':
				return len - 1;
		  }
		}

		return len;
	  }

	  private int norm2(char[] s, int len)
	  {
		if (len > 8)
		{
		  if (s[len - 1] == 'e' || s[len - 1] == 'o' || s[len - 1] == 'u')
		  {
			len--;
		  }
		}

		if (len > 4)
		{
		  if (s[len - 1] == 'i')
		  {
			len--;
		  }

		  if (len > 4)
		  {
			char ch = s[0];
			for (int i = 1; i < len; i++)
			{
			  if (s[i] == ch && (ch == 'k' || ch == 'p' || ch == 't'))
			  {
				len = StemmerUtil.delete(s, i--, len);
			  }
			  else
			  {
				ch = s[i];
			  }
			}
		  }
		}

		return len;
	  }

	  private bool isVowel(char ch)
	  {
		switch (ch)
		{
		  case 'a':
		  case 'e':
		  case 'i':
		  case 'o':
		  case 'u':
		  case 'y':
			  return true;
		  default:
			  return false;
		}
	  }
	}

}